According to FDA records, 5-Hour Energy has been mentioned in 90 case filings since 2009, including 30 that cited life-threatening injuries like heart attacks, convulsions and one case of "spontaneous abortion." Last month, the agency acknowledged that it was investigating a possible link between the energy drink Monster and five deaths.

While the filing of a complaint with the agency doesn't necessarily mean the product is harmful, the FDA is looking into whether the supplement may have played a part in the injuries and deaths. The distributor of the product, Living Essentials, hasn't disclosed the amount of caffeine it contains, but an article published by Consumer Reports put the level somewhere around 215 milligrams. An eight-ounce cup of coffee, by contrast, contains between 100-150 milligrams.

Living Essentials, meanwhile, says the product is safe when used as directed and that they're "unaware of any deaths proven to be caused by the consumption of 5-Hour Energy.”